On Wed, Nov 07, 2012 at 11:58:10AM -0800, Andrew Morton wrote:
> On Wed, 7 Nov 2012 01:05:52 -0200
> Rafael Aquini <aquini@xxxxxxxxxx> wrote:
>
> > Memory fragmentation introduced by ballooning might reduce significantly
> > the number of 2MB contiguous memory blocks that can be used within a guest,
> > thus imposing performance penalties associated with the reduced number of
> > transparent huge pages that could be used by the guest workload.
> >
> > Besides making balloon pages movable at allocation time and introducing
> > the necessary primitives to perform balloon page migration/compaction,
> > this patch also introduces the following locking scheme, in order to
> > enhance the syncronization methods for accessing elements of struct
> > virtio_balloon, thus providing protection against concurrent access
> > introduced by parallel memory migration threads.
> >
> > ...
> >
> > @@ -122,18 +128,25 @@ static void set_page_pfns(u32 pfns[], struct page *page)
> >
> > static void fill_balloon(struct virtio_balloon *vb, size_t num)
> > {
> > + struct balloon_dev_info *vb_dev_info = vb->vb_dev_info;
> > +
> > + static DEFINE_RATELIMIT_STATE(fill_balloon_rs,
> > + DEFAULT_RATELIMIT_INTERVAL,
> > + DEFAULT_RATELIMIT_BURST);
> > +
> > /* We can only do one array worth at a time. */
> > num = min(num, ARRAY_SIZE(vb->pfns));
> >
> > + mutex_lock(&vb->balloon_lock);
> > for (vb->num_pfns = 0; vb->num_pfns < num;
> > vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
> > - struct page *page = alloc_page(GFP_HIGHUSER | __GFP_NORETRY |
> > - __GFP_NOMEMALLOC | __GFP_NOWARN);
> > + struct page *page = balloon_page_enqueue(vb_dev_info);
> > +
> > if (!page) {
> > - if (printk_ratelimit())
> > + if (__ratelimit(&fill_balloon_rs))
> > dev_printk(KERN_INFO, &vb->vdev->dev,
> > "Out of puff! Can't get %zu pages\n",
> > - num);
> > + VIRTIO_BALLOON_PAGES_PER_PAGE);
> > /* Sleep for at least 1/5 of a second before retry. */
> > msleep(200);
> > break;
>
> linux-next's fill_balloon() has already been converted to
> dev_info_ratelimited(). I fixed everything up. Please check the result.
Looks great, thanks for doing it
>
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